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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Wet Waste Hydrothermal Liquefaction and Biocrude Upgrading to Hydrocarbon Fuels (2019 State of Technology)

Each year, the DOE Bioenergy Technologies Office (BETO) assesses progress in their research and development efforts toward sustainable production of renewable fuels. Technical and cost targets were previously established for the wet waste hydrothermal liquefaction and biocrude upgrading pathway and summarized in a design report. The present report summarizes the research and associated techno-economic analysis (TEA) in support of the 2019 state of technology (SOT) assessment for this pathway. Data from Pacific Northwest National Laboratory’s Conversion hydrothermal liquefaction (HTL) program for wet waste was used to update the pathway techno-economic analysis (TEA) for the fiscal year 2019 State of Technology (2019 SOT). An overview of the current process model, experimental data and plant economics for the SOT is presented.

09 BIOMASS FUELS↗
DOE OSTI2022

Salt-Assisted 2H-to-1T' Phase Transformation of Transition Metal Dichalcogenides [plus supplemental information]

Phase engineering of nanomaterials (PEN) has demonstrated great potential in the fields of catalysis, electronics, energy storage and conversion, and condensed matter physics. Recently, transition metal dichalcogenides (TMDs) with unconventional metastable phases (e.g., 1T and 1T') have attracted increasing research interest due to their unique and appealing physicochemical properties. However, there is still a lack of a simple, universal, and controlled method for the preparation of large-scale and high-purity unconventional-phase TMD crystals, restricting their further fundamental study and practical applications. Here, a facile, one-step salt-assisted general strategy is reported for the controlled phase transformation of commercially available TMDs with conventional 2H phase, yielding a large amount of metastable 1T'-phase TMDs, including WS 2 , WSe 2 , MoS 2 , and MoSe 2 . It is found that the easily accessible metal salts, such as K 2 C 2 O 4 ·H 2 O, K 2 CO 3 , Na 2 CO 3 , Rb 2 CO 3 , Cs 2 CO 3 , KHCO 3 , NaHCO 3 , and NaC 2 O 4 , can be used to assist the 2H-to-1T' phase transformation, greatly simplifying the synthetic process for producing metastable 1T'-TMDs. Importantly, this method can also be used to prepare 1T'-TMD alloys, such as 1T'-WS 2x Se 2(1–x) . We report this newly developed strategy is robust and highly effective, which can also be used for the phase engineering of other materials with various polymorphs.

1T′ phase↗
DOE OSTI2022

Thermodynamic guiding principles of high-capacity phase transformation materials for splitting H 2 O and CO 2 by thermochemical looping

Here, thermochemical looping splitting of water and carbon dioxide (CO 2 ) with greenhouse-gas-free (GHG-free) energy has the potential to help address the Gt-scale GHG emissions challenge. Reaction thermodynamics largely contributes to the main bottlenecks of cost reduction for thermochemical looping water/CO 2 splitting cycle. Here, we analyze thermodynamic driving forces in such cycles with two-phase ternary ferrites as model systems. We find that cation configurational entropy chiefly determines the change of partial molar entropy with oxygen stoichiometry. In addition, our phase diagram analysis accurately predicts the optimal Fe ratio for maximal water/CO 2 splitting capacity in thermal reduction and in chemical reduction based cycles, underlining the significance of phase boundary positions. With chemical reduction, >10% CO 2 conversion and high oxygen exchange capacity can both be achieved. Furthermore, our reduced Gibbs free energy model illustrates critical thermodynamic factors that influence the water/CO 2 splitting capacity. Our research reveals the thermodynamic driving forces underlying the unconventional high-capacity Fe-poor ferrites, further explained via phase diagrams of Fe–Co–O, Fe–Ni–O and Fe–Mg–O. Future materials improvements can be guided by our reduced Gibbs free energy model.

08 HYDROGEN↗
DOE OSTI2022

Quadratic strong coupling in AlN Kerr cavity solitons

Photonic platforms with χ (2) nonlinearity offer new degrees of freedom for Kerr frequency comb development. Here, we demonstrate Kerr soliton generation at 1550 nm with phase-matched quadratic coupling to the 775 nm harmonic band in a single AlN microring and thus the formation of dual-band mode-locked combs. In the strong quadratic coupling regime where the χ (2) phase-matching window overlaps the pump mode, the pump-to-harmonic-comb conversion efficiency is optimized. However, the strong quadratic coupling also drastically modifies the Kerr comb generation dynamics and decreases the probability of soliton generation. By engineering the χ (2) phase-matching wavelength, we are able to achieve a balance between high conversion efficiency and high soliton formation rate under the available pump power and microring quality factors. Our numerical simulations confirm the experimental observations. These findings provide guidance on tailoring single-cavity dual-band coherent comb sources.

Gong, Zheng (ORCID:0000000301704870)↗
DOE OSTI2025

Effect of stress on Laves phase precipitation in creep ruptured Grade 92 ferritic martensitic steel characterized by a novel accessible method

At high temperature conditions relevant to fossil and nuclear energy plants, Laves phase (Fe 2 X, X=Mo, W) precipitation is observed in common ferritic martensitic (FM) structural steels, with various reported effects on creep behavior. Despite being valuable metrics to correlate with mechanical properties and other precipitate phases, the volume fraction and number density of Laves phase precipitates has been difficult to quantify accurately using common techniques such as transmission electron microscopy (TEM) due to the relatively large size (∼0.25 μm) and low number density (∼10 11 cm −3 ) of Laves precipitates. Here, to address this characterization challenge, we developed and demonstrated a high-throughput and widely accessible method to quantify the volume fraction and number density of the Laves phase based on scanning electron microscope (SEM) images with a backscattered electron signal and the information depth (ID) of backscattered electrons. We applied this new technique in creep ruptured Grade 92 FM steel to study the effect of Laves phase on creep properties and determine the influence of stress on Laves phase precipitation. The quantitative accuracy of the SEM-based volume fraction and number density values was verified using synchrotron high energy X-ray diffraction and serial sectioning tomography. Stress did not significantly affect the Laves phase size or volume fraction during creep testing at 550 – 650°C and stress levels of 90 – 260 MPa (vs. unstressed conditions). Conversely, a moderate but statistically significant stress-enhanced increase in Laves phase number density, corresponding to an increase in nucleation rate, occurred during creep exposure above 110 MPa.

Creep↗
DOE OSTI2024

Solution-Processable Polymer Donor-Small Molecule Acceptor Bulk Heterojunction Organocatalysts for Enhancing CO 2 -to-CO Photoconversion

Metal-free organic semiconductors have emerged as a kind of promising star material in photocatalysis. However, their photocatalytic efficacy is impeded by the great recombination rate of the photogenerated charge carriers. Herein, we demonstrate the devising of solution-processable organic semiconductor bulk heterojunction (BHJ) systems with varying ratios by using BP3DT and PC 61 BM as the donor (D) and acceptor (A) candidates, respectively, for enhanced selective CO production from CO 2 photoreduction. The prepared BP3DT/PC 61 BM BHJs are solution-processed on both glass substrates (GS) and molecular sieves (MS) via a drop-casting technique to form an active thin film and porous photocatalysts to catalyze CO production. All BP3DT/PC 61 BM BHJs efficiently produce CO as the primary product in the existence of trace-level TEA/H 2 O (0.5 mL). Our results show that the photocatalytic efficiency depended on the D/A w% ratios and its nanoscale phase separation morphology within the BHJ, contributing to the promotion of exciton dissociation. Additionally, the BHJ undergoes an ostensible morphological transition from large-scale phase-separation to a fine mixed homogeneous nanoscale by varying the BP3DT/PC 61 BM blend ratio from 30/70 w% to 70/30 w%, which increases the interfacial area and shortens the distance of the exciton to the D/A surface, and promotes charge carrier separation, corroborated by photo-optical and photoelectrochemical experimental results. Accordingly, the resulting BP3DT/PC 61 BM BHJ@MS with a D/A ratio of 70/30 w% achieves a CO yield of 819 μmol·g cat -1 h -1 , surpassing those of pure PC 61 BM (126 μmol·g cat -1 h -1 ) and BP3DT (72 μmol·g cat -1 h -1 ) by 6.5- to 11.3-fold and also exceeding that of metal-free linear conjugated polymer-based organocatalysts reported to date. Specifically, this is the first work to develop an organic-semiconductor-based BHJ photocatalyst, which may offer a nascent way to design more efficient organocatalysts for CO 2 reduction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Phase-Exchange-Driven Wake-Up and Fatigue in Ferroelectric Hafnium Zirconium Oxide Films

Ferroelectric hafnium zirconium oxide holds great promise for a broad spectrum of complementary metal–oxide–semiconductor (CMOS) compatible and scaled microelectronic applications, including memory, low-voltage transistors, and infrared sensors, among others. An outstanding challenge hindering the implementation of this material is polarization instability during field cycling. Herein, the nanoscale phenomena contributing to both polarization fatigue and wake-up are reported. Using synchrotron X-ray diffraction, the conversion of non-polar tetragonal and polar orthorhombic phases to a non-polar monoclinic phase while field cycling devices comprising noble metal contacts is observed. This phase exchange accompanies a diminishing ferroelectric remanent polarization and provides device-scale crystallographic evidence of phase exchange leading to ferroelectric fatigue in these structures. A reduction in the full width at half-maximum of the superimposed tetragonal (101) and orthorhombic (111) diffraction reflections is observed to accompany wake-up in structures comprising tantalum nitride and tungsten electrodes. Combined with polarization and relative permittivity measurements, the observed peak narrowing and a shift in position to lower angles is attributed, in part, to a phase exchange of the non-polar tetragonal to the polar orthorhombic phase during wake-up. These results provide insight into the role of electrodes in the performance of hafnium oxide-based ferroelectrics and mechanisms driving wake-up and fatigue, and demonstrate a non-destructive means to characterize the phase changes accompanying polarization instabilities.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Development of organic-inorganic hybrid selective layers via vapor phase infiltration to enhance the durability of perovskite solar cells

Despite the rapid increase in power conversion efficiency (PCE) of perovskite solar cells (PSCs) over the last decade, stability remains a major roadblock to commercialization. This work proposes the use of vapor phase infiltration (VPI) as a tool to create hybrid organic-inorganic layers that improve the stability of organic charge transport layers, such as hole-selective spiro-OMeTAD in these PSC and other organic electronic devices. Using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and grazing incident wide-angle X-ray scattering (GIWAXS), we identify that infiltration of TiO X via VPI hinders the crystallization of the spiro-OMeTAD layer by likely preventing the π- π stacking of the molecules. Infiltrated PSCs retained around 80% of their original efficiency after an operando stability test of 60 h at 75 °C, double the efficiency retained by devices without infiltration. This work provides a blueprint for using VPI to stabilize organic charge transport layers via prevention of π- π stacking that leads to deleterious crystallization that shortens device lifetimes.

14 SOLAR ENERGY↗
DOE OSTI2024

Mathematical Modeling of Multi-Phenomena Anisotropic Systems: Ejection of Primary Aerosols during the Fast Pyrolysis of Biomass

This study introduces a novel particle model for biomass fast pyrolysis, incorporating an anisotropic cylindrical particle to address mass and energy transport coupled with aerosol ejection, which previous models have overlooked. The main contribution lies in developing a model that considers aerosol generation in anisotropic cylindrical particles for the first time, addressing bubbling dynamics and bursting within the liquid phase. The population balance equation describes bubble dynamics and aerosol formation, capturing phenomena like nucleation, growth, coalescence, and bursting. The model employs the method of moments with bubble volume as an internal variable, substantially reducing computational costs by eliminating dependence on this variable. Results highlight the significant impact of anisotropy and particle size on aerosol ejection: smaller, less elongated particles experience faster heating, quicker conversion, and the increased accumulation of the liquid intermediate phase. Specifically, 1 mm diameter particles yield higher concentrations of metaplast and bio-oil aerosols, exceeding 15%, compared to concentrations below 11% for 3 mm particles. This model provides insights into aerosol structure (volume, surface area), aiding in understanding aerosol reactivity at the reactor scale.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Mechanistic pathways and role of oxygen in oxidative coupling of methane derived from transient kinetic studies

Oxidative coupling of methane (OCM) is a promising industrial process to upgrade natural gas to high value chemicals. In this study, Temporal Analysis of Products (TAP) and steady-state experiments were conducted to distinguish how the composition of surface and gas phase oxygen influence mechanistic details of the selective conversion of CH 4 to C 2 H 4 over the Mn-Na 2 WO 4 /SiO 2 catalyst. The results from TAP studies indicate that methane activation on this catalyst proceeds predominantly via a short-lived, transient surface oxygen species and there is a competition for this species to form either CO or methyl radicals on the surface. This active species has a total lifetime of 3 s and is identified to have a dioxygen (e.g. O 2 2- or O 2 -) form. We show that the concentration of the transient surface oxygen species significantly impacts the OCM performance. Oxygen attributed to the catalyst lattice (in a singular form e.g., O - ), is found to activate methane to a lesser degree, but exclusively forms CO 2 . Evidence for these surface pathways for methyl radical, CO and CO 2 formation identified by TAP are also validated through steady-state experiments. Finally, by distinguishing different catalyst oxygen species and their role in selective/nonselective pathways, important screening criteria have been identified for the advancement of superior catalyst formulations.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Effects of co-adsorbed water on different bond cleavages involved in acetic acid decomposition on Pt (111)

Acetic acid decomposition on Pt (111) in the presence of co-adsorbed water is a good model system for oxygenate decomposition on Pt (111) in aqueous phase, with application in hydrogen production and biomass conversion. Here, in this study, we present a density functional theory (DFT) theory calculation of how co-adsorbed water affects different bond cleavages of acetic acid decomposition on Pt (111). The presence of co-adsorbed water generally enhances O$-$H bond cleavage while inhibiting OC$-$O and OC$-$OH bond cleavage. The influence of co-adsorbed water on C$-$H bond cleavage varies the most and depends on the nature of the transition state and how co-adsorbed water stabilizes the initial and final state. Although these trends are useful as general guidance, they are not sufficient to predict the effect on a complex reaction network such as acetic acid decomposition on Pt (111) which has several parallel reaction paths with similar energies. In the absence of co-adsorbed water, the two lowest energy pathways are decarboxylation (DCX) and decarbonylation (DCN) pathways through a common CH 2 COO intermediate, in which the DCX pathway (C$-$H bond cleavage of CH 2 COO) is more favorable than DCN pathway (OC$-$O bond cleavage of CH 2 COO). In the presence of co-adsorbed water, the energy difference between Csingle bondH bond cleavage and OC$-$O bond cleavage of CH 2 COO increases, suggesting an increase in the favorability of acetic acid decarboxylation (formation of carbon dioxide) over acetic acid decarbonylation (formation of carbon monoxide) on Pt (111).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Revealing Mesoscale Ionomer Membrane Structure by Tender Resonant X-ray Scattering

Nafion, a perfluorosulfonic acid ionomer, has been well-studied for decades due to its key role as an ion-conductive membrane in electrochemical energy conversion and storage applications. When hydrated, this membrane phase separates into a complex hierarchical nanostructure with hydrophilic domains that facilitate ion transport. Hard X-ray scattering has been a powerful technique in understanding Nafion due to its capabilities in capturing the ionomer’s nanophase separated structure, which gives rise to contrast between polymer and water domains. More recently, resonant X-ray scattering, which tunes to elemental absorption edges to provide specificity on constituent elements, has been explored to highlight key interactions related to the sulfonic acid groups within its structure. Here, in this work, we study the Nafion nanostructure by combining hard X-ray scattering and tender resonant X-ray scattering (TReXS) at the sulfur K-edge to reveal a mesoscopic feature corresponding to a correlation length of approximately 40 nm that has been challenging to resolve with hard X-ray studies. Additionally, we study the effect of the dispersion solvent composition that plays a key role in the formation of this mesoscale feature. Notably, TReXS can attain high contrast to decipher this mesoscale morphology even for dry polymer membranes under a vacuum, which typically have reduced contrast for hard X-rays. We find that the correlation length of this mesoscale feature decreases with increasing water fraction in the dispersion, which is the opposite trend exhibited by the smaller intercrystalline feature in the same membranes. This study showcases the utility of TReXS to uncover multiscale morphological details in functional polymers that are not always revealed by other methods like hard X-ray scattering. We illustrate this with Nafion, which is a relevant ion-conducting polymer for electrochemical technologies.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Atomic Structural Origin of the High Methanol Selectivity over In 2 O 3 –Metal Interfaces: Metal–Support Interactions and the Formation of a InO x Overlayer in Ru/In 2 O 3 Catalysts during CO 2 Hydrogenation

CO 2 hydrogenation to methanol is of great environmental and economic interest due to its potential to reduce carbon emissions and produce valuable chemicals in one single reaction. Compared with the unmodified traditional Cu/ZnO/Al 2 O 3 catalyst, an indium oxide (In 2 O 3 )-based catalyst can double the methanol selectivity from 30–50 to 60–100%. It is worth noting that over catalysts involving various active metals dispersed on indium oxide (M/In 2 O 3 , M = Pd, Ni, Au, etc.), although the methanol yield is boosted, the selectivity remains similar to that of plain In 2 O 3 despite the distinct chemical properties of the added metals. Here, to investigate the phenomena behind this behavior, we used RuO 2 /In 2 O 3 as a test catalyst. The results of ambient pressure photoelectron spectroscopy, in situ X-ray absorption fine structure, and time-resolved X-ray diffraction indicate that the structure of the RuO 2 /In 2 O 3 catalyst is highly dynamic in the presence of a reactive environment. Specifically, under CO 2 hydrogenation conditions, Ru clusters facilitate the reduction of In 2 O 3 to generate In 2 O 3–x aggregates, which encapsulate the Ru systems in a migration driven by thermodynamics. In this way, the Ru O sites for CH 4 production are blocked while creating RuO x –In 2 O 3–x interfacial sites with tunable metal–oxide interactions for selective methanol production. In an inverse oxide/metal configuration, indium oxide has properties not seen in its bulk phase that are useful for the binding and conversion of CO 2 . This work reveals the dynamic nature of In 2 O 3 -based catalysts, providing insights for a rational design of materials for the selective synthesis of methanol.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Designing high-power, octave spanning entangled photon sources for quantum spectroscopy

Entangled photon spectroscopy is a nascent field that has important implications for measurement and imaging across chemical, biology, and materials fields. Entangled photon spectroscopy potentially offers improved spatial and temporal-frequency resolutions, increased cross sections for multiphoton and nonlinear measurements, and new abilities in inducing or measuring quantum correlations. A critical step in enabling entangled photon spectroscopies is the creation of high-flux entangled sources that can use conventional detectors as well as provide redundancy for the losses in realistic samples. Here, we report a periodically poled, chirped, lithium tantalate platform that generates entangled photon pairs with ~10 -7 efficiency. For a near watt level diode laser, this results in a near μW-level flux. The single photon per mode limit that is necessary to maintain non-classical photon behavior is still satisfied by distributing this power over up to an octave-spanning bandwidth. The spectral–temporal photon correlations are observed via a Michelson-type interferometer that measures the broadband Hong–Ou–Mandel two-photon interference. A coherence time of 245 fs for a 10 nm bandwidth in the collinear case and a coherence time of 62 fs for a 125 nm bandwidth in the non-collinear case are measured using a CW pump laser and, essentially, collecting the full photon cone. We outline in detail the numerical methods used for designing and tailoring the entangled photons source, such as changing center wavelength or bandwidth, with the ultimate aim of increasing the availability of high-flux UV–Vis entangled photon sources in the optical spectroscopy community.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Experimental and computational studies on high-entropy carbide MoNbTaVWC 5 under high pressures

High-entropy carbide, MoNbTaVWC 5 , was synthesized from oxide precursors of the constituent metals, mixed with graphite powder in a microwave-generated hydrogen plasma at 26.66 kPa and 2100 °C. Ambient x-ray diffraction analysis confirms the full conversion of oxide precursors into a single-phase, face-centered cubic structure with a lattice parameter a = 4.3309 Å. Nanoindentation measured a hardness of 24.5 ± 1.3 GPa and an elastic modulus of 386 ± 22 GPa. The synthesized sample, mixed with a copper pressure marker, was studied by the radial x-ray diffraction technique with beryllium gasketing in a diamond anvil cell up to 70 GPa. The experimentally measured pressure–volume curve and shear strength were compared with theoretical predictions using the special quasi-random structure technique and density functional theory. MoNbTaVWC 5 achieved a 12% volume compression at 70 GPa and exhibited a high shear strength of 6.6 GPa. The present study demonstrates that the high-entropy carbide MoNbTaVWC 5 exhibits exceptional incompressibility and high strength under extreme conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Enabling Ultra-Compact, Lightweight, Efficient, and Reliable 6.6 kW On-Board Bi-Directional Electric Vehicle Charger with Advanced Topology and Control

The research explored new topologies, control methods, mechanical integration, and thermal management methods for electric vehicle (EV) on-board chargers. The team investigated capacitor-based power conversion, leveraging the high energy densities inherent to capacitive energy storage compared to inductive methods. The proposed topologies simultaneously enabled high power density and high efficiency of the design. The proposed architecture was demonstrated in a 6.6 kW bi-directional charger prototype. The research pursued several directions to improve system performance. Innovative topologies were studied for both the main power conversion stage as well as the single-phase twice-line-frequency energy buffer. To ensure robust and efficient operation, new control methods were developed to integrate these two subsystems. To achieve high power density in the full system solution, the mechanical structure of the charger is highly optimized to maximally fill the converter box volume. In parallel with the mechanical design effort, the converter was packaged with high-performance cooling methods which removed heat from key areas of power dissipation in the converter. The thermal management system was optimized to minimize its weight and volume, ultimately motivating the design of a custom additively manufactured cold-plate. The full system achieves a peak power of 7 kW with less than 0.3% total harmonic distortion (THD) and greater than 0.994 power factor in power factor correction (PFC) operation, corresponding to a total box-volume power density of 47.9 kW/L and gravimetric power density of 24.6 W/g. The system achieves a peak efficiency of 98.9%, with 97.9% efficiency at maximum power.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2023

CO Oxidation Catalyzed by Au Dispersed on SBA-15 Modified with TiO2 Films Grown via Atomic Layer Deposition (ALD)

It has been established that gold, when in nanoparticle (NP) form and in contact with reducible oxides, can promote oxidation reactions under mild conditions. Here, we report results from our exploration of the catalytic oxidation of carbon monoxide using catalysts where Au NPs were combined with thin titanium oxide films deposited on SBA-15 using atomic layer deposition (ALD). Both orders of deposition, with TiO2 added either before or after Au dispersion, were tested for two titania film thicknesses amounting to about half and full TiO2 monolayers. The resulting catalysts were characterized using various techniques, mainly electron microscopy and N2 adsorption–desorption isotherms, and the kinetics of the oxidation of CO with O2 were followed using infrared absorption spectroscopy. A synergy between the Au and TiO2 phases as it relates to the bonding and conversion of CO was identified, the tuning of which could be controlled by varying the synthetic parameters. The ALD of TiO2 films proved to be an effective way to maximize the Au-TiO2 interface sites, and with that help with the activation of molecular oxygen.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

High-fidelity and high-resolution phase mapping of granites via confocal Raman imaging

Abstract In physical sciences such as chemistry and earth sciences, specifically for characterization of minerals in a rock, automated, objective mapping methods based on elemental analysis have replaced traditional optical petrography. However, mineral phase maps obtained from these newer approaches rely on conversion of elemental compositions to mineralogical compositions and thus cannot distinguish mineral polymorphs. Secondly, these techniques often require laborious sample preparations such as sectioning, polishing, and coating which are time-consuming. Here, we develop a new Raman imaging protocol that is capable of mapping unpolished samples with an auto-focusing Z-mapping feature that allows direct fingerprinting of different polymorphs. Specifically, we report a new methodology for generating high fidelity phase maps by exploiting characteristic peak intensity ratios which can be extended to any multi-phase, heterogenous system. Collectively, these enhancements allow us to rapidly map an unpolished granite specimen (~ 2 × 2 mm) with an exceptionally high accuracy (> 97%) and an extremely fine spatial resolution (< 0.3–2 µm).

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗